For many years, it has been at least implicitly assumed that environmental stresses were important to the etiology of several disease states such as reduced immunity to infection and cardiovascular diseases. In recent years, experimental evidence has been accumulating which implicates behavioral stress as an important risk factor in the development of cardiovascular pathologies. The work proposed in this research project is aimed at the comprehensive description of the cardiovascular changes which occur before, during and as a consequence of controlled behavioral stress. This is to be accomplished by measuring several major cardiovascular parameters simultaneously in conscious dogs in both normal and stressful environments. Subsequent studies will investigate the role of the nervous system in the observed changes by selective surgical denervation of the heart.